SN-MMR of 1 or greater mitoses/mm2 demonstrated significant correlation with—and was the strongest independent predictor for—OS, MSS, and DFS (all P ≤ .0006). SNB also had a moderate-to-strong correlation with the S and Rotterdam classifications, MTD, and TPD with Spearman’s correlation coefficient range of 0.51 to 0.69 (P < .0001 for each).

Of the patients with a positive SNB, 28.1% had an SN-MMR of 1 or more mitoses/mm2. Patients with an SN-MMR of 1 or higher mitoses/mm2 had a 5-year MSS rate of 45.5% and 5-year DFS of 22.2%, compared with 87.9% and 67.3%, respectively, for patients with an SN-MMR of 0 mitoses/mm2. The 5-year OS rate was 45% vs 87% for patients with an SN-MMR of greater than or equal to 1 or less than 1, respectively.

“None of the other classification systems showed a similar discriminative power to stratify patients with slowly and rapidly progressive disease with regard to OS, MSS, and DFS,” wrote the authors.

The TPD, MTD, number of positive SNs, Breslow index, S-, Dewar, Rotterdam, Hannover I, and Hannover II were also significantly correlated with OS, and MSS, and—except for number of positive SNs—DFS. The authors indicated that these data were similar to other published cohorts of patients with SN-positive melanoma.

“The study correlated SN-MMR and other classifications to the outcome, and therefore no definite conclusions can be drawn with regard to treatment recommendations,” Dr Géraud told Cancer Therapy Advisor. He noted, however, that “to define the impact of an SN-MMR greater than or equal to 1 should have on the management of stage 3 melanoma patients, it will be necessary to incorporate its routine assessment and evaluation into clinical trials.”

The authors recommend that SN-MMR be incorporated into the standard pathology reports immediately for all patients with SNB-positive melanoma, though they acknowledge that further multicentric analyses are needed.

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Dr Géraud said that “assessment and reporting of the SN-MMR should be quite easy for every pathologist and dermatopathologist that is familiar with the evaluation of primary excisions and sentinel node biopsies of patients with melanoma.” He noted that the methodology of SN-MMR determination is similar to that recommended by the AJCC for the staging of primary melanomas, and additional equipment or staining procedures are not required.

References

  1. Baum C, Weiss C, Gebhardt C, et al. Sentinel node metastasis mitotic rate (SN-MMR) as a prognostic indicator of rapidly progressing disease in patients with sentinel node-positive melanomas. Intl J Cancer. 2016 Dec 9. doi: 10.1002/ijc.30563 [Epub ahead of print]